The invention relates to a self-jamming safety device for a rope, comprising:
a first base flange equipped with a first pulley or fixed stud, which is offset with respect to an articulation spindle extending perpendicular to the first flange,
a second pulley securedly united to a support plate mounted with limited pivoting around the spindle in a parallel plane to the base flange,
an operating handle associated with the support plate to provide manual releasing of the rope,
a second retractable flange arranged to allow the rope to be wound and to pass between the first and second pulleys,
a first braking surface arranged on the first pulley, against which the rope is pressed by a boss of the second pulley when the support plate is driven by the tension of the rope to a first jamming position,
and a return spring biasing the support plate in the releasing direction to a rest position.
A device of this kind is known from the document FR 2,451,752 corresponding to the STOP descender marketed by the applicant. The reaction of the rope urges the second pulley to a single jamming position, in which the boss jams the rope against the first braking surface. A pivoting travel limiting stop is arranged on the support plate to stop the second pulley in this position. The jamming effect by the boss can however damage the rope when large shocks are incurred following repeated falls.
The object of the invention consists in achieving a safety device which can be used as a descender or a jammer, preventing premature wear of the rope.